//圈地测面积,不是我写的,https://www.jianshu.com/p/4a97d3ed4a06
export default function measureAreaSpace() {
    let Cesium = this.Cesium;
    let viewer = this.viewer;

    // 取消双击事件-追踪该位置
    viewer.cesiumWidget.screenSpaceEventHandler.removeInputAction(Cesium.ScreenSpaceEventType.LEFT_DOUBLE_CLICK);
    // 鼠标事件
    let handler = new Cesium.ScreenSpaceEventHandler(viewer.scene._imageryLayerCollection);
    var positions = [];
    var tempPoints = [];
    var polygon = null;
    // var tooltip = document.getElementById("toolTip");
    var cartesian = null;
    var floatingPoint;//浮动点
    // tooltip.style.display = "block";

    handler.setInputAction(function (movement) {
        // tooltip.style.left = movement.endPosition.x + 3 + "px";
        // tooltip.style.top = movement.endPosition.y - 25 + "px";
        // tooltip.innerHTML ='<p>单击开始，右击结束</p>';
        // cartesian = viewer.scene.pickPosition(movement.endPosition); 
        let ray = viewer.camera.getPickRay(movement.endPosition);
        cartesian = viewer.scene.globe.pick(ray, viewer.scene);
        //cartesian = viewer.scene.camera.pickEllipsoid(movement.endPosition, viewer.scene.globe.ellipsoid);
        if (positions.length >= 2) {
            if (!Cesium.defined(polygon)) {
                polygon = new PolygonPrimitive(positions);
            } else {
                positions.pop();
                // cartesian.y += (1 + Math.random());
                positions.push(cartesian);
            }
            // tooltip.innerHTML='<p>'+distance+'米</p>';
        }
    }, Cesium.ScreenSpaceEventType.MOUSE_MOVE);

    handler.setInputAction(function (movement) {
        // tooltip.style.display = "none";
        // cartesian = viewer.scene.pickPosition(movement.position); 
        let ray = viewer.camera.getPickRay(movement.position);
        cartesian = viewer.scene.globe.pick(ray, viewer.scene);
        // cartesian = viewer.scene.camera.pickEllipsoid(movement.position, viewer.scene.globe.ellipsoid);
        if (positions.length == 0) {
            positions.push(cartesian.clone());
        }
        //positions.pop();
        positions.push(cartesian);
        //在三维场景中添加点
        var cartographic = Cesium.Cartographic.fromCartesian(positions[positions.length - 1]);
        var longitudeString = Cesium.Math.toDegrees(cartographic.longitude);
        var latitudeString = Cesium.Math.toDegrees(cartographic.latitude);
        var heightString = cartographic.height;
        tempPoints.push({ lon: longitudeString, lat: latitudeString, hei: heightString });
        floatingPoint = viewer.entities.add({
            name: '多边形面积',
            position: positions[positions.length - 1],
            point: {
                pixelSize: 5,
                color: Cesium.Color.RED,
                outlineColor: Cesium.Color.WHITE,
                outlineWidth: 2,
                heightReference: Cesium.HeightReference.CLAMP_TO_GROUND
            }
        });
    }, Cesium.ScreenSpaceEventType.LEFT_CLICK);

    handler.setInputAction(function (movement) {
        handler.destroy();
        positions.pop();
        //tempPoints.pop();
        // viewer.entities.remove(floatingPoint);
        // tooltip.style.display = "none";
        //在三维场景中添加点
        // var cartographic = Cesium.Cartographic.fromCartesian(positions[positions.length - 1]);
        // var longitudeString = Cesium.Math.toDegrees(cartographic.longitude);
        // var latitudeString = Cesium.Math.toDegrees(cartographic.latitude);
        // var heightString = cartographic.height;
        // tempPoints.push({ lon: longitudeString, lat: latitudeString ,hei:heightString});

        var textArea = getArea(tempPoints) + "平方公里";
        viewer.entities.add({
            name: '多边形面积',
            position: positions[positions.length - 1],
            // point : {
            //  pixelSize : 5,
            //  color : Cesium.Color.RED,
            //  outlineColor : Cesium.Color.WHITE,
            //  outlineWidth : 2,
            //  heightReference:Cesium.HeightReference.CLAMP_TO_GROUND 
            // },
            label: {
                text: textArea,
                font: '18px sans-serif',
                fillColor: Cesium.Color.GOLD,
                style: Cesium.LabelStyle.FILL_AND_OUTLINE,
                outlineWidth: 2,
                verticalOrigin: Cesium.VerticalOrigin.BOTTOM,
                pixelOffset: new Cesium.Cartesian2(20, -40),
                heightReference: Cesium.HeightReference.CLAMP_TO_GROUND
            }
        });
    }, Cesium.ScreenSpaceEventType.RIGHT_CLICK);

    var radiansPerDegree = Math.PI / 180.0;//角度转化为弧度(rad) 
    var degreesPerRadian = 180.0 / Math.PI;//弧度转化为角度

    //计算多边形面积
    function getArea(points) {

        var res = 0;
        //拆分三角曲面

        for (var i = 0; i < points.length - 2; i++) {
            var j = (i + 1) % points.length;
            var k = (i + 2) % points.length;
            var totalAngle = Angle(points[i], points[j], points[k]);


            var dis_temp1 = distance(positions[i], positions[j]);
            var dis_temp2 = distance(positions[j], positions[k]);
            res += dis_temp1 * dis_temp2 * Math.abs(Math.sin(totalAngle));
            // console.log(res);
        }


        return (res / 1000000.0).toFixed(4);
    }

    /*角度*/
    function Angle(p1, p2, p3) {
        var bearing21 = Bearing(p2, p1);
        var bearing23 = Bearing(p2, p3);
        var angle = bearing21 - bearing23;
        if (angle < 0) {
            angle += 360;
        }
        return angle;
    }
    /*方向*/
    function Bearing(from, to) {
        var lat1 = from.lat * radiansPerDegree;
        var lon1 = from.lon * radiansPerDegree;
        var lat2 = to.lat * radiansPerDegree;
        var lon2 = to.lon * radiansPerDegree;
        var angle = -Math.atan2(Math.sin(lon1 - lon2) * Math.cos(lat2), Math.cos(lat1) * Math.sin(lat2) - Math.sin(lat1) * Math.cos(lat2) * Math.cos(lon1 - lon2));
        if (angle < 0) {
            angle += Math.PI * 2.0;
        }
        angle = angle * degreesPerRadian;//角度
        return angle;
    }

    var PolygonPrimitive = (function () {
        function _(positions) {
            this.options = {
                name: '多边形',
                polygon: {
                    hierarchy: [],
                    // perPositionHeight : true,
                    material: Cesium.Color.GREEN.withAlpha(0.5),
                    // heightReference:20000
                }
            };

            this.hierarchy = { positions };
            this._init();
        }

        _.prototype._init = function () {
            var _self = this;
            var _update = function () {
                return _self.hierarchy;
            };
            //实时更新polygon.hierarchy
            this.options.polygon.hierarchy = new Cesium.CallbackProperty(_update, false);
            viewer.entities.add(this.options);
        };

        return _;
    })();

    function distance(point1, point2) {
        var point1cartographic = Cesium.Cartographic.fromCartesian(point1);
        var point2cartographic = Cesium.Cartographic.fromCartesian(point2);
        /**根据经纬度计算出距离**/
        var geodesic = new Cesium.EllipsoidGeodesic();
        geodesic.setEndPoints(point1cartographic, point2cartographic);
        var s = geodesic.surfaceDistance;
        //console.log(Math.sqrt(Math.pow(distance, 2) + Math.pow(endheight, 2)));
        //返回两点之间的距离
        s = Math.sqrt(Math.pow(s, 2) + Math.pow(point2cartographic.height - point1cartographic.height, 2));
        return s;
    }
}